Sometimes you can wait for another person for a long time, but it is bearable; other times it is a burden.

What factors make the difference?

Apparently, no research has been done about this topic. Personal observation seems to point to certain conclusions:

When you know that the other party is aware of the fact that you are waiting for them at this very moment, then even an extended wait is more bearable.

In other words, the time itself is not the sole factor.

However, if you are waiting and the other side is not aware that you are waiting for them at this very moment, or they are not aware that you have already arrived at the agreed upon place, then a small wait seems interminable and a longer wait may be so difficult that you would not even try to imagine doing it.

Thus, it seems that your perception of the other party's knowledge is the determining factor in your own ability to deal with an extended wait.

This is the problem with an aguna or a prisoner of war - POW. Neither of these people knows whether the other side cares or knows about the fact that they are waiting. This could be an extremely cruel situation. A prisoner of war can more readily maintain his sanity if he knows that his loved ones are praying for and working towards his release.